It is well known that trailers, particularly of a four-wheel type, have a tendency to weave or sway, particularly at high speeds and this problem is aggravated when a number of vehicles are interconnected in a train of vehicles. It has heretofore been proposed, for example as shown in U.S. Pat. Nos. 2,612,382; 3,400,948; 3,414,295 and 3,519,287, to provide a friction type brake for frictionally retarding swaying movement between the towing and trailing vehicles. Such friction type brakes, however, apply a generally constant braking action independent of the relative angular position of the towing and trailing vehicles and it has been found that the use of such friction type brakes alone is not satisfactory to overcome the problem of swaying of vehicles in a train when the train is drawn along a straight path at moderate to high speeds.